1. Field of the Invention
The invention relates to extensions for rotatable control devices including a rotatable control shaft extending outwardly from a body housing a control means, wherein the extension is connected between the control shaft and an elongated operating handle for operating the control means. In one aspect, the invention relates to extensions for quarter-turn valves, such as ball valves, butterfly valves and plug valves.
2. Reference to Prior Art
Manually operated valves for controlling fluid flow through piping systems typically include a body having a flow passage extending therethrough, a valve member such as a rotatable ball disposed in the body, a control shaft or stem connected to the valve member and extending out of the body, an operating handle operably connected to the stem for moving the valve member between open and closed positions, and stops on the body for limiting rotation of the operating handle between the open and closed positions. In particular, quarter-turn valves having elongated operating handles are conventionally configured so that the longitudinal axis of the operating handle is parallel to the flow passage when the valve is open and perpendicular to the flow passage when the valve is closed. Therefore, the orientation of the handle provides a ready visual indication of whether the valve is open or closed.
An extension is connected between the operating handle and stem when it is necessary to space the operating handle from the valve body, such as when the valve is in a location which is difficult to reach or when the valve body is encased in insulation. An extension may be added either during assembly of the new valve at the factory, or may be sold separately in a retrofit kit for installation on the valve in the field. When an extension is used, it is possible that the operating handle can be installed relative to the valve stem and flow passage in an orientation different from the position in which it was originally installed at the factory or otherwise intended to be installed.
When an extension is added to a quarter-turn valve, it is possible that the extension will be installed on the stem and the operating handle installed on the extension so the operating handle is aligned opposite from the conventional orientation, i.e., the longitudinal axis of the operating handle extending perpendicularly to the flow passage when the valve is open and extending parallel to the flow passage when the valve is closed. When the operating handle of a quarter-turn valve is aligned opposite from the conventional orientation, the visual indication provided by the position of the handle relative to the flow passage is inaccurate. As a result, although personnel are generally instructed to manually verify whether valves are open or closed, personnel failing to manually verify the condition of the valve can erroneously believe that the valve is open when it is actually closed, or vice-versa. The same is true when an inspection is made during system operation. This kind of error can cause a variety of process problems, such as shutting off water to a fire sprinkler system, spilling fluid from the piping system, and unintendedly introducing fluid into portions of the piping system.
Quarter turn valves typically include packing around the valve stem to prevent leakage of fluid from the flow passage through space around the valve stem. Valves having "draw-down" packing around the valve stem typically include packing such as felt, an annular gland follower, a pull-down plate for forcing the gland follower down against the packing to compress the packing around the stem, and pull-down screws spaced radially outwardly from the stem and extending through holes in the pull-down plate into threaded cavities in the valve body for forcing or "pulling" the plate down against the gland follower. The pull down screws are diametrically spaced relative to the rotational axis of the stem, and the heads of these screws can act as stops for the operating handle.
U.S. Pat. No. 4,756,507 to McAndrew, discloses a ball or plug valve extension and lock mechanism. The valve extension includes a rod member to extend the valve stem. The rod member has a lower end bored and threaded to threadably engage the exposed end of the valve stem. Set screws extend horizontally into the bore to bear on the sides of the valve stem to align the rod with the valve stem. When the handle is turned, the valve stem is turned by the rod and set screws, and the set screws prevent the rod from loosening. The valve does-not include pull-down packing.
Two stem extensions are disclosed in Neles-Jamesbury Bulletin B-160-3 (Neles-Jamesbury, Inc., 1988). In one arrangement, the operating handle, stop arm and extension are a one-piece unit which is operably connected to the outer end of the valve stem. Stops on the valve body adjacent to the valve stem body are spaced ninety degrees from each other. In the second arrangement, the stop arm is welded to the inner end of the extension, the extension is threaded onto the outer end of the valve stem, and the operating handle is removably mounted on the outer end of the extension. In neither arrangement does the valve include pull-down packing.